Why did Napoleon sell the United States the Louisiana territory in the early 1800s?

The Louisiana territory was a pawn chess piece of land in North America throughout the second half of the 18th century. It was controlled by the French who had a few small settlements along the Mississippi River and other main rivers.

France ceded the territory to Spain in the secret 'Treaty of Fountainebleau' in 1762. Then, following the French defeat in the Seven Years War (a European war involving many nations at the time from 1756-1763), Spain gained control of the territory west of the Mississippi and the British gained the territory to the east of the river.

Prior to its purchase by the United States, France regained ownership of the Louisiana territory in 1800 from Spain and Napoleon hoped to re-establish an empire in North America. The Haitian Revolution (1791-1804) however had been a successful anti-slavery and anti-colonial insurrection by self-liberated slaves against French colonial rule in Saint-Domíngue- establishing the sovereign nation of Haiti.

France's failure to put down the revolt in Saint-Domíngue, coupled with the prospect of renewed warfare with the United Kingdom, prompted Napoleon to sell Louisiana to the United States to fund his military.

The 'Louisiana Purchase' (French= Vente de la Louisiana) was the largest territorial gain in U.S. history in 1803. The U.S. paid 50 million francs ($11,250,000 USD) and a cancellation of debts worth 18 million francs ($3,750,000) This amount was 15 million equivalent to $607 million in USD in 2018.